The United States and Japan will step up their defence cooperation to deal with the threat from nuclear-armed North Korea as tensions in East Asia remain high, officials from the two allies said on Thursday.

London attack had 'hallmarks of terror'

The deadly van attack near a mosque in north London had "all the hallmarks of a terrorist incident," police say.

The man suspected of being the driver has been arrested on suspicion of attempted murder, and no other suspects have been identified or reported to police, Deputy Assistant Commissioner Neil Basu told reporters on Monday.

All the victims were Muslim, Basu said.

One person was killed and eight people were taken to hospital and two others were treated at the scene.

Basu said at least two of the injured were in serious condition.

The suspect "was very quickly and calmly given over to the police," Basu said, as he praised the community.

It shows that "Londoners will act together to protect themselves, and will do so in a way that doesn't feed into terrorists' hands."